Note that at this point in time, while it's under discussion as part of the overall general philosophy, there's no allowance for other-than-USDM engines...
I just don't understand why. engine displacement - look at chart - get weight, race. who cares if it ever displaced that much in a car sold in america or not?? the rules spec CR, lift, and weight by displacement and don't take ANY other engine characteristic (STL valve count differences excluded) into account - TB size, head flow, shrouding, RSR, B:S, whatever. we can verify lift, CR and displacement EASILY, in impound, with simple, common tools. And in many cases it's minimally invasive (valve cover and spark plugs)
intakes, non-US market engines, ignitions, etc... should ALL be open UNLESS the motor is from a specline, in which case it must conform to that line. keeping conformity to all stock specs (except those specifically open/different in the STCS) and then saying the nissan, ford, VW, and toyota, etc... of 2.5L should all be making the same power is patently ludicrous. yeah, they'll probably be close - but there's no way to be sure. keeping the
bore, stroke, deck height, heads, etc... as factory or with allowed porting DOES provide for variation and should be controlled for the sake of cost containment - but how doe s aRHD only motor or one not sold in the US for whatever reason take away from this? mandate english language, manufacturer published basic engine specs to ensure the competitor isn't "making" a motor (cost control) but otherwise let them in.
it will cost me the same to get a NON US toyota gen 3 3S-GE 2.0L non-turbo motor from a 94-97 celica or MR2, WITH A TRANSMISSION, as it will to convert my USDM Gen 1 86-89 celica motor to shim under bucket (already this way in gen 3) so that I can use the cams allowed in STU. other than that, it's a different intake, SMALLER head ports, and oiling and other minor changes that are basically irrelevant in the eyes of the ST rules. it made a not scary high ~170hp from the factory, and there are THOUSANDS of them out there. why is this not allowed??? it's just friggin stoopid.